# SN74LS123DBR

**Texas Instruments** · Monostable Multivibrators · SSOP-16-208mil

SN74LS123DBR from Texas Instruments, in a SSOP-16-208mil. Pinout and pin descriptions extracted from the manufacturer datasheet (extract_pins, cross-checked by a second model); symbol, footprint, and 3D from KiCad-official CAD.

## Pinout

| Pin | Name | Type | Function |
|---|---|---|---|
| 1 | 1A | input | Multivibrator 1 trigger input A, triggered on its falling edge (high-to-low transition) while 1B is high and 1CLR is high. |
| 2 | 1B | input | Multivibrator 1 trigger input B, triggered on its rising edge while 1A is low and 1CLR is high, with Schmitt hysteresis for slow transitions down to 0.1 mV/ns. |
| 3 | 1CLR | input | Multivibrator 1 active-low clear input that terminates the output pulse when taken low, with a 17 kΩ nominal input resistance. |
| 4 | ~{1Q} | output | Multivibrator 1 complementary (active-low) pulse output, rated for IOL up to 8 mA and IOH of -400 µA for the SN74LS123. |
| 5 | 2Q | output | Multivibrator 2 true pulse output, rated for IOL up to 8 mA and IOH of -400 µA for the SN74LS123. |
| 6 | 2Cext | passive | Multivibrator 2 external timing capacitor terminal (negative side), where Cext has no restriction on value. |
| 7 | 2Rext/Cext | passive | Multivibrator 2 external timing resistor/capacitor junction, with Rext from 5 kΩ to 260 kΩ to VCC for the SN74LS123 and wiring capacitance limited to 50 pF max. |
| 8 | GND | power_in | Ground; all voltage values in the datasheet are referenced to this network ground terminal. |
| 9 | 2A | input | Multivibrator 2 trigger input A, triggered on its falling edge (high-to-low transition) while 2B is high and 2CLR is high. |
| 10 | 2B | input | Multivibrator 2 trigger input B, triggered on its rising edge while 2A is low and 2CLR is high, with Schmitt hysteresis for slow transitions down to 0.1 mV/ns. |
| 11 | 2CLR | input | Multivibrator 2 active-low clear input that terminates the output pulse when taken low, with a 17 kΩ nominal input resistance. |
| 12 | ~{2Q} | output | Multivibrator 2 complementary (active-low) pulse output, rated for IOL up to 8 mA and IOH of -400 µA for the SN74LS123. |
| 13 | 1Q | output | Multivibrator 1 true pulse output, rated for IOL up to 8 mA and IOH of -400 µA for the SN74LS123. |
| 14 | 1Cext | passive | Multivibrator 1 external timing capacitor terminal (negative side), where Cext has no restriction on value. |
| 15 | 1Rext/Cext | passive | Multivibrator 1 external timing resistor/capacitor junction, with Rext from 5 kΩ to 260 kΩ to VCC for the SN74LS123 and wiring capacitance limited to 50 pF max. |
| 16 | VCC | power_in | Supply voltage, recommended 4.75 V to 5.25 V for the SN74LS123 with an absolute maximum of 7 V. |

## Key specifications

| Parameter | Value |
|---|---|
| Manufacturer | Texas Instruments |
| Package | SSOP-16-208mil |
| Category | Logic |
| Pins | 16 |

## CAD (KiCad official)

- Symbol: `SN74LS123DBR`
- Footprint: `Package_SO:SSOP-16_5.3x6.2mm_P0.65mm`
- 3D model: SSOP-16-208mil (KiCad packages3D, STEP)
- 3D model files: `sn74ls123dbr-etched.step` / `sn74ls123dbr-etched.glb` carry the MPN laser-etched on the die in a toggleable `Adom.LaserEtch` group (Fusion-ready); `sn74ls123dbr.step` / `sn74ls123dbr.glb` are the bare package body.

## Provenance

Data extracted from the manufacturer datasheet, not a distributor listing:

- **Datasheet:** [Texas Instruments datasheet](https://www.ti.com/lit/ds/symlink/sn74ls123.pdf) (32 pp, sha256 `24c30d3b1087b33e`, retrieved 2026-11-05, tier: manufacturer)
- **Extractor:** parts-factory `2.0.0` / `extract_pins 0.3`, primary `claude-sonnet-5-5` (text+vision), consensus `claude-opus-5-5` (agreed), guards: pin_guards 0.1: passed. Pins are checked against the footprint pad set and their cited datasheet pages before publish.
- **CAD:** KiCad official libraries (CC-BY-SA 4.0).

[Datasheet PDF](docs/sn74ls123dbr-datasheet.pdf)